The increased use of microwaves for cooking has given rise to a large market in microwavable foods. While the advantage of microwave cooking over convection oven cooking is the time savings, the disadvantage is that certain baked goods (e.g., cookies and pot pies) do not develop the surface browning or crust formation expected with convection oven cooking.
Our objective is to create that browning which enhances the products' appearance, making it look as if it were cooked in a convection oven.
In the microwave, food does not have sufficient time or temperature for the chemicals responsible for browning to react. Therefore, for a microwave browning system to work, it must accelerate the rate of the browning reactions or locally increase the surface temperature. Ultimately, the reactions responsible for browning have to be accomplished in the relatively short time frame dictated by the foods' preparation conditions. The times needed for preparing microwave foods vary depending upon the power output of the microwave unit and the mass of the food to be cooked and the nature of the food to be cooked. A typical 750 watt microwave apparatus will cook baked goods foodstuffs in 6 to 15 minutes.
Several additional requirements for a successful microwave browning system are as follows:
1. In addition to the desired browning effect, it must generate either no aroma or one which is compatible with the target foodstuff;
2. The browning reaction must not take place before cooking the foodstuff;
3. After cooking, the browning must stop, and not darken the foodstuff substantially.
The reactions responsible for browning during convection oven cooking are the caramelization of sugars and the Maillard reaction between naturally occurring reducing sugars, amino acids, amines, peptides and proteins which results in the formation of colored melanoidins. Until recently (1984) there were numerous patent and literature references to such reactions for the production of flavors, where the generation of color was inconsequential or objectionable. In the past few years several patents have appeared wherein microwave browning created by Maillard reactions have been the topic. Thus, Bryson, et al in United States Letters Patent 4,735,812 issued on Apr. 5, 1988 discloses a browning agent particularly for use in microwave cooking comprising collagen or gelatin hydrolyzed to its constituent amino acids plus one or more reducing sugars and alkalis. It is further indicated in Bryson, et al that the collagen preferably is derived from Bovine hides, and that the alkalis are preferably a mixture of sodium carbonate and bicarbonate. It is further indicated that the browning agent may be incorporated into a film or used as a powder or liquid.
Parliment et al, United States Letters Patent 4,857,340 issued on Aug. 15, 1989 discloses a composition of an aroma producing material enrobed in a fusible encapsulating agent, preferably a lipid and in conductive heat transfer relationship with a microwave susceptible material when combined with a microwave comestible or package for providing an aroma when the comestible or package is prepared by subjecting the comestible or package and composition to microwave energy.
Kim et al, "Formation of Volatile Compounds from Maillard Reaction of D-Glucose with DL-Alanine in Propylene Glycol Solution", Han'guk Sikp'um Kwahakhoechi 1988, 20(2), 157-63 (Korea), (Abstracted at Chemical Abstracts Volume 112 at 34512q) discloses volatile compounds produced from the browning reaction of alanine and glucose using propylene glycol as a reaction medium.
Although the prior art does take advantage of the reaction between reducing sugars and amino acids, it has not made any correlation of reaction rates needed for browning reactions with reaction variables such as pH, solvent, or sugar reactivity in connection with browning reactions concerning the surface of baked goods such as cookies and pot pies.